The presence of abundant (>10%) hydrothermally precipitated magnetite with associated copper–iron sulfides in the breccias hosting the mineralization suggests a deposit type such as an iron oxide–copper–gold (IOCG). However, there are features of the Boa Esperança deposit that do not match the proposed IOCG deposit type. Among these are the presence of high sulfur mineral assemblage (chalcopyrite–pyrite), rather than the low sulfur copper sulfide mineral assemblage characteristic of the IOCG deposit type (chalcopyrite–bornite–chalcocite), as well as the high quartz content, the absence of pervasive hydrothermal alteration of the host rock, specifically sodic (albite) alteration, and the absence of gold. As such, the Boa Esperança copper deposit is interpreted to be a variant of an IOCG deposit type.

IOCG deposits are classified as separate from other large intrusive-related copper deposits such as porphyry copper deposits and other porphyry metal deposits, primarily due to their substantial accumulations of iron oxide minerals, association with felsic–intermediate type intrusions (Na-Ca rich granitoids), and lack of the complex zonation in alteration mineral assemblies commonly associated with porphyry deposits.

The Boa Esperança deposit displays primary and secondary zoning. The primary zoning corresponds to a distal zone, where pyrite (py) dominates, grading towards copper mineralized zones of pyrite–chalcopyrite (py–cpy), chalcopyrite–pyrite (cpy–py) ........

The planned Boa Esperança mine will use conventional open pit mining techniques and diesel mining equipment to mine a total of 203 Mt of material over the LOM. This will consist of 54 Mt of ore and 149 Mt of waste material. Selective mine practices will be applied avoiding dilution. The operation will include normal drilling, blasting loading with 5.2 m3/3.9m3 (waste/ore) backhoe configured excavator and 38 t conventional trucks over an 8 m bench height (double bench of 16 m in fresh rock in interim and final slopes). Mining will be performed on a sub-bench of flitch basis to improve selectivity.

The mine plan was developed by NCL. The plan is focused on a single mine area, mined through consecutive mining phases or pushbacks. The mill throughput is based on an economic throughput assessment study, resulting in an average throughput of 4.0 Mtpa of sulphide ore and a ramp-up period of 12 months that assumes a production rate of 3.2 Mt in the first year of production. Production starts during the second quarter of Year 1 to avoid the rainy season.

The required pre-stripping amounts to 13.2 Mt, and activities have been scheduled over 24 months, starting in Year -2 quarter 2, through Year 1 quarter 1. The mining schedule requires an average mine extraction of 20 Mtpa. The mine movement decreases from Year 10 until the mining operations are completed in Year 12.

The mine is scheduled to work on a seven-days-a-week, three 8-hour shift basis, for 365 ........

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